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Baffle plugs - is there more elegant solution?

Vlad

Well Known Member
Little details here. Spark plug access holes on newer baffle kits are of oblong shape. Plans say use two Tinnerman washers AN3235 screwed together. There is still a gap and it doesn't look right because metal is thinner than the washers. I was looking at others builders' websites and nobody has those spark plug access holes. Can somebody comment on these or post a picture?
 
Had the same

Vlad,

I used a Van's o-320 baffle kit to do my O-235. I cut a piece of .032 aluminum the same shape as the oblong hole you describe, but bigger so it overlapped the hole on all sides and used an avex 1601-410 rivet (any pop rivet would do) at the top of it and can now slide the larger piece back and forth to expose the sparkplug access hole whenever necessary. Works great.
 
Similar problem the other way

Little details here. Spark plug access holes on newer baffle kits are of oblong shape. Plans say use two Tinnerman washers AN3235 screwed together. There is still a gap and it doesn't look right because metal is thinner than the washers. I was looking at others builders' websites and nobody has those spark plug access holes. Can somebody comment on these or post a picture?

The new Lycoming that I had put in my RV6 in 2003 came with round grommets to fit a round hole in the baffle. There were two plug wires to a grommet. Apparently, that style of grommet is no longer made, which is probably why your baffle kit has oblong holes.

When I was helping a friend with his baffles recently, he had the opposite problem you describe. The grommets he had were oblong, figure-eight-shaped and the hole in the baffle was round. We searched all over to find round grommets like mine to fit his round holes but couldn't find them. Spruce only had the oblong ones.

So I think if you look in the Spruce catalog, you'll find some oblong grommets to fit your holes. I'd give you a link but I couldn't find them on the web site. They were hard to find in the book.
 
same baffle kit as you...

Vlad,

Do you have the baffle material on yet? You can't almost, but not quite, cover the hole with the tinnerman, but the baffling helps out. Between the baffling and the tinnermans, I was able to plug the hole. A pic probably doesn't help much, and it's a lousy pic at that. I cut a slit in the baffling there, and the lower edge of the baffling is sandwiched between the tinnermans.

web.jpg
 
Thank you all gentlemen. All examples are very useful and now I have an idea what to fabricate.
 
One other issue you need to be aware of if not done, will give you an elevated temp on #3. Not sure whether the instructions have been updated.

Make sure you add a washer between the #3 cylinder backside to the baffle. Without the washer, air can not pass over #3 and the back of the cylinder/baffle.
Someone on this list gave me the fix. I had been chasing this for quite some time. Once done, it lowered my #3 cht by 20-25 degrees.
 
Hi,
I am wondering what those spark plug access holes are for? I don’t understand the interest of those holes . That’s rather a leaky point .
 
To enable you to put an extension on end of your socket to get the plug out...
At least on my 10, i can't fit a plug socket and the wrench inside of the baffle, need the extension through the hole, wrench on the outside.

Phil
 
Spark plug wires

I bought two of these. Requires a little cutting and drilling but they fit perfect. I'll try and figure out where I got them. I haven't plugged the access holes yet but plan a couple pieces of aluminum pre-treated with sealant then a #8 screw and nut.
20220626_102333.jpg
 
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One other issue you need to be aware of if not done, will give you an elevated temp on #3. Not sure whether the instructions have been updated.

Make sure you add a washer between the #3 cylinder backside to the baffle. Without the washer, air can not pass over #3 and the back of the cylinder/baffle.
Someone on this list gave me the fix. I had been chasing this for quite some time. Once done, it lowered my #3 cht by 20-25 degrees.


Yep, I put 3 washers there... #3 is now 30F cooler. Even cooler than #1.
I might remove 1 washer...

As for the Spark Plug holes, I used what Vans suggested and there was still a gap.
As I don't have to go through these holes to install/remove the plugs, I filled the gaps with Red RTV.
 
Yep, I put 3 washers there... #3 is now 30F cooler. Even cooler than #1.
I might remove 1 washer...

As for the Spark Plug holes, I used what Vans suggested and there was still a gap.
As I don't have to go through these holes to install/remove the plugs, I filled the gaps with Red RTV.

Don’t remove a washer.. get some aluminum foil tape and raise the front airdam on #1. Them if you need, you can also add some on #2 and really balance out the CHTs
 
To enable you to put an extension on end of your socket to get the plug out...
At least on my 10, i can't fit a plug socket and the wrench inside of the baffle, need the extension through the hole, wrench on the outside.

Phil

So you can inspect cylinder #3 or #4 top spark plug ? Ok .
But I prefer to close that hole, and without leakages .
Thanks
 
Spark plug socket

I just looked at mine. My plug socket has a hex shaped end for a wrench. Used it many times in tight spaces. No need to try and fish an extension through those holes so I'm going to seal them.
 
good suggestion

Don’t remove a washer.. get some aluminum foil tape and raise the front airdam on #1. Them if you need, you can also add some on #2 and really balance out the CHTs
thanks Tom, good suggestion, I'll try that...
 
aviation plugs

I just looked at mine. My plug socket has a hex shaped end for a wrench. Used it many times in tight spaces. No need to try and fish an extension through those holes so I'm going to seal them.

If one is using the aviation plugs, I think using a wrench on a plug socket is fine. But if one is using an automotive type plug, I think access through the baffle would prevent tweaking the plugs during install. (Of course removal of auto plugs doesn't matter, since we all throw them away after one use. Right??)
 
If one is using the aviation plugs, I think using a wrench on a plug socket is fine. But if one is using an automotive type plug, I think access through the baffle would prevent tweaking the plugs during install. (Of course removal of auto plugs doesn't matter, since we all throw them away after one use. Right??)

That's the plan although I have no idea what tweaking a plug means. :D
I figure if I can R&R the plugs in the back two cylinders of a late model V8, I can get plugs in or out of my Lycoming. I can see those! The V8 requires me climbing up into the engine bay with a socket, universal, 6" extension and wratchet while cursing and praying the blasted things come out.That's after hopefully removing the coil pack in one piece. That rarely happens. :D
 
I just cut out a piece of baffle seal material slightly larger than the oval hole, punched a hole in the middle for the screw, and sandwiched it between the two washers to seal the opening completely. I have aviation plugs on mine, and may need those openings for wrench access.
 
Being a simple guy, I just took some aluminum metal tape and taped a small piece over the hole on the inside of the baffle. I got tired of messing with the tinnerman washers and metal lock nut. At annual or whenever I need to look at one of the back plugs, I just pull off the tape. Then I put another piece on when I am done. Simple and a perfect complete seal.

Keith.
 
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